Image Segmentation Improvements

[alee001]

I greatly appreciate MP's image segmentation function, especially the batch processing capability.

Here are some suggestions for improvement:

1) Add a selection of free-scale segmentation lines. (Blue line)

2) Add the option to segment only using custom boundaries. (Red line)

3) Add the ability to sort segmented images. (e.g., the order of image names can be reversed left/right or top/bottom)